1. Field of the Invention
The present invention relates to a film image input device and method, and more particularly to a film image input device and method suitable for a film scanner which illuminates developed color film and reads the transmitted image light by scanning it with a CCD line sensor.
2. Description of the Related Art
A film image input device such as a film scanner performs shading correction in order to eliminate the unevenness of pixels in an image sensor such as a charge coupled device (CCD), the unevenness of the quantity of light in a lamp for illuminating the film, a characteristic error in an optical system, or the like. In the conventional methods, a shading correction plate, which has the same color and transmission factor as a base area of the negative film, is inserted so as to obtain the shading correction data, or the shading correction data are obtained via a negative base area on the film (Japanese Patent Provisional Publication No. 6-152953).
In a conventional film scanner, if there are a plurality of film types that can be loaded in the scanner, a user inputs the type of a mounted film cartridge, or the scanner reads bar codes recorded on the film so as to identify the film type (Japanese Utility Model Provisional Publication No. 2-3546).
The method in which the shading correction plate is inserted, however, has a disadvantage because the operation is complicated. In the method in which the shading data are obtained via the negative base area on the film, the correct data cannot be obtained due to grain coarseness on the film if the determination is performed on only one point of the negative base area. Thus, a plurality of points covering a wide area of the negative base must be scanned to obtain the mean value. In the case of the film which does not have a wide negative base area or in which the density of the negative base differs with the part due to stains, in that case the correct data cannot be obtained.
Moreover, if the user sets the film type in advance, the operation becomes more complicated. The method in which the bar codes on the film are read has a disadvantage because the device is large in size and is more expensive.